Allow setting global variables through the CLI

Closes #192

internal/args/args.go

@@ -1,36 +1,43 @@
 package args
 
 import (
-	"errors"
 	"strings"
 
 	"github.com/go-task/task/v2/internal/taskfile"
 )
 
-var (
-	// ErrVariableWithoutTask is returned when variables are given before any task
-	ErrVariableWithoutTask = errors.New("task: variable given before any task")
-)
-
 // Parse parses command line argument: tasks and vars of each task
-func Parse(args ...string) ([]taskfile.Call, error) {
+func Parse(args ...string) ([]taskfile.Call, taskfile.Vars) {
 	var calls []taskfile.Call
+	var globals taskfile.Vars
 
 	for _, arg := range args {
 		if !strings.Contains(arg, "=") {
 			calls = append(calls, taskfile.Call{Task: arg})
 			continue
 		}
+
 		if len(calls) < 1 {
-			return nil, ErrVariableWithoutTask
-		}
+			if globals == nil {
+				globals = taskfile.Vars{}
+			}
 
-		if calls[len(calls)-1].Vars == nil {
-			calls[len(calls)-1].Vars = make(taskfile.Vars)
-		}
+			name, value := splitVar(arg)
+			globals[name] = taskfile.Var{Static: value}
+		} else {
+			if calls[len(calls)-1].Vars == nil {
+				calls[len(calls)-1].Vars = make(taskfile.Vars)
+			}
 
-		pair := strings.SplitN(arg, "=", 2)
-		calls[len(calls)-1].Vars[pair[0]] = taskfile.Var{Static: pair[1]}
+			name, value := splitVar((arg))
+			calls[len(calls)-1].Vars[name] = taskfile.Var{Static: value}
+		}
 	}
-	return calls, nil
+
+	return calls, globals
+}
+
+func splitVar(s string) (string, string) {
+	pair := strings.SplitN(s, "=", 2)
+	return pair[0], pair[1]
 }